This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. To goal of this project is to determine if developmental maturity of the pulmonary mucosal immune system plays a significant role in the establishment of an effective immune response against influenza infection. Specific Aim #1: Determine the timing and magnitude of protective T cell responses following influenza infection in infant NHPs. We propose that cytotoxic T cell responses are delayed and deficient in infant nonhuman primates. To test this hypothesis, the timing of viral clearance and establishment of protective immunity will be evaluated in infant monkeys infected with influenza virus. Specific Aim #2: Define the impact of increased age on establishment of an efficient mucosal immune response against influenza infection. We propose that juvenile animals, will have mature T lymphocytes and an experienced mucosal immune system facilitating a more rapid and robust response to influenza infection as compared to the younger animals. Proposed studies will compare T cell-mediated immunity and ability to eradicate virus in juvenile and infant monkeys.